Method for the preparation of low-chloride plaster products from calcium-containing residues of flue-gas purification plants

US5324501A · kind A · utility

Assignee

• A.I.R. Lippewerk Recycling GmbH · DE

Inventors

• Diethel M. Koehnk · Bergkamen, DE
• Hubert Bings · Grafenau, DE

Key dates

• Filing date: Mar 2, 1992
• Grant date: Jun 28, 1994
• Expiry date: Mar 2, 2012

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01F11/468
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

Disclosed herein is a method for producing plasters that contain chloride contents of less than 0.5% by weight from calcium-containing impure products or residues having a high chloride content (e.g., about 10% or higher based on the total product or residue weight). The method does not require the addition of fly ash, SiO.sub.2 or Al.sub.2 O.sub.3. The method comprises temperature and water-mediated conversion of calcium chloride to calcium oxide in the calcium-containing product or residue using water, steam and/or substances that generate water to obtain calcium oxide and hydrochloric acid; and sulfating calcium components in the product or residue using oxygen and sulfur-containing, largely calcium-free substances. The product so obtained is an anhydride plaster which can optionally be hydrated.